[JENKINS-28379] Allow FingerprintFacet to block the deletion of Fingerprint

[stellargo]

See JENKINS-28379.

Proposed changelog entries

Proposed upgrade guidelines

N/A

Submitter checklist

• JIRA issue is well described
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  • Fill-in the Proposed changelog entries section only if there are breaking changes or other changes which may require extra steps from users during the upgrade
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Desired reviewers

@mention

Maintainer checklist

Before the changes are marked as ready-for-merge:

• There are at least 2 approvals for the pull request and no outstanding requests for change
• Conversations in the pull request are over OR it is explicit that a reviewer does not block the change
• Changelog entries in the PR title and/or Proposed changelog entries are correct
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• If it would make sense to backport the change to LTS, a JIRA issue should exist and be labeled as lts-candidate

[rsandell]

What is the current use case for this? Can you provide a downstream PR with an example for where you need it?

[MRamonLeon]

@oleg-nenashev do you think this feature is still needed? thanks

[stellargo]

@MRamonLeon I am quoting below Oleg's response on Gitter.

The codebase around fingerprints in Jenkins was quite stable over past 4 years, so old tickets should be still relevant. Let me know if you need any additional pointers.

I would just add a new API method for keeping fingerprint forever, e.g. FingerprintFacet#isKeepFingerprintForever() which defaults to false. Then any Facet implementation can check the flag. At the same time the Jenkins core will be able to consult with facets before deleting a fingerprnt

[oleg-nenashev]

I am not sure you want to introduce a new field for fingerprintDeletionBlocked at all. There is no API consumers at the moment. Maybe it is better to just implement an overridable isFingerprintDeletionBlocked() which returns false by default.

P.S: Sorry for the late reviews, catching up

[oleg-nenashev]

Looks good to me, thanks @stellargo !

[alecharp]

@stellargo please, don't force-push on PR when it war already review by some people: it's hard to track the changes.

[alecharp]

I have no problem with the PR but asking few syntax improvements. Also would like to open the discussion about the return null and the need for the annotation on the public API.

[stellargo]

@alecharp Thanks for the review! I’ve made the requested changes. Let me know if anything more is required.

[oleg-nenashev]

Thanks for addressing the comments. I believe we can merge it, just a single comment about the naming

[stellargo]

Thanks @oleg-nenashev , I have made the requested changes.

[oleg-nenashev]

I plan to merge it tomorrow if no negative feedback

[oleg-nenashev]

ATH is stuck due to infra issues. I will ignore it and merge the PR. It was passing before

[oleg-nenashev]

Thanks for your contribution @stellargo !

[stellargo]

Thanks @oleg-nenashev and everyone who guided me through it. I learnt a lot :)